[llvm] Add CMake configure preset building blocks (PR #170019)

[Richard Thomson via llvm-commits]

LegalizeAdulthood wrote:

Since I have commit access and this is purely opt-in for other developers and has no impact on existing builds or workflows, I'm going to merge this PR after it's been up for a week unless there are objections.

https://github.com/llvm/llvm-project/pull/170019